And I'm Linda Wertheimer. The Guardian newspaper is promising more revelations about the NSA's secret, worldwide surveillance programs. The revelations so far have been based on documents and interviews with just one man - Edward Snowden, a former IT contractor at the NSA hired by the firm Booz Allen Hamilton.

Snowden leaked numerous documents about the U.S. intelligence system, and made dramatic claims about what he was able to do within that system. But as NPR's Steve Henn reports, many in the tech industry and the intelligence establishment have doubts.

STEVE HENN, BYLINE: In Edward Snowden's interview with The Guardian newspaper, the 29-year-old IT consultant made some extraordinary claims.

EDWARD SNOWDEN: Any analyst, at any time, can target anyone.

HENN: Snowden said that intelligence analysts and private contractors - like himself - could tap into virtually any conversation.

SNOWDEN: Not all analysts have the ability to target everything. But I, sitting at my desk, certainly had the authorities to wiretap anyone; from you or your accountant, to a federal judge to even the president, if I had a personal email.

HENN: So is this plausible?

CARRIE CORDERO: No.

HENN: Carrie Cordero is the director of national security studies at Georgetown University Law Center.

CORDERO: The notion that this individual has the authority to go ahead and quote-unquote, "wiretap people" is just ridiculous.

HENN: Before Cordero moved to academia, she was a national security lawyer at the Justice Department, and the officer of the director of National Intelligence. [POST-BROADCAST CLARIFICATION: Cordero has been a national security lawyer at the Justice Department, and at the Office of the Director of National Intelligence.] Now, she can't discuss the nuts and bolts of how these surveillance systems work, but...

CORDERO: I can tell you that that quote from him does not resemble anything close to what I observed in the intelligence community, in the duration that I worked with the community.

HENN: So Snowden might not have had the legal authority to wiretap anyone, but did he have the ability? Where these systems built in a way that even made that possible?

Now, there is no doubt that the NSA is collecting a tremendous amount of data about our communication. Susan Freiwald is a cyber lawyer and privacy expert at University of San Francisco.

SUSAN FREIWALD: It's now clear that Verizon and several other of the major telecom companies have been asked on a rolling basis for all metadata - telephony metadata - for all their customers.

HENN: But that so-called metadata doesn't include the content of conversations. It's like a master file of which numbers connect to which other numbers - and how long the people on both ends talk. For an analyst sitting in Hawaii to initiate a wiretap - a real wiretap - on anyone anywhere, he or she would need much, much more.

That analyst would need access to an archive of the content of every communication;and the ability to monitor new calls, emails and chats in real time. Cordero says it's illegal to do any of this without a specific court order.

CORDERO: And a collection system is going to be designed in accordance with the law. They're not going to design a collection system that is going to invite violations of the law.

HENN: And technology company executives have said, in no uncertain terms, that they are not granting the NSA unfettered access to their servers - or turning over data on the scale necessary to make a system like that work.

FREIWALD: I think it's quite likely that they're telling the truth.

HENN: Still, Susan Freiwald - at USF - says the secrecy that surrounds these FISA court orders to Internet companies makes it impossible for anyone outside the intelligence community to know just how invasive this system really is.

FREIWALD: And I think it's also possible that things were going on in their companies that they didn't know about. So for that reason, I think there's still a lot to learn about exactly what was happening.

HENN: Right now, companies that receive FISA court orders are forbidden by law from talking about them. But yesterday, Google, Microsoft and Facebook all asked the Justice Department and the FBI for permission to publicly disclose the number and scope of FISA orders they receive each year.